1. Field of the Invention
This invention relates to fire resistant safety glass and methods for production. Specifically, this invention relates to improved glass for the construction industry that provides increased safety and reduction of injuries upon breakage comprising wire glass and either a fire resistant film or another piece of fire resistant glazing material.
2. Description of Related Art
Wire glass continues to be widely used in the construction industry to provide transparent windows, doors, walls and the like. Wire glass generally consists of glass having a mesh of steel or other wire embedded within the glass. The use of wire glass has been motivated by a desire to provide transparent structures that are more resistant to fire than glasses having no wire. The wire in the glass holds the glass together in fire situations. Wire glass is commonly used in schools, public buildings, and other structures that are subject to fire. Typically, as used in schools, wire glass is used in hallways, gymnasium doors and walls. One drawback of wire glass is that if a person impacts the wire glass structure, the glass may break, the wire will keep the pane relatively intact, and this increases the danger of a person becoming injured.
Unfortunately, when broken, conventional wire glass is dangerous. For example, upon impact, the glass in a pane of wire glass can become broken into sharp pieces (shards) and the wire can actually hold the shards together to form a highly dangerous “spider-web” structure. In situations in which a person's extremity (arm or leg) actually penetrates through a broken portion of a pane of conventional wire glass, the damage can become so severe as to require major surgical procedures to repair the damage. In some cases, the limb must be amputated, and in other, more serious situations, death due to exanguination may occur.
FIG. 1a depicts a drawing of a pane of prior art wire glass 100 in top view. Glass 104 has wire mesh 108 embedded therein. FIG. 1b depicts a drawing of a pane of prior art wire glass 100 shown in cross-section. Glass 104 has wire mesh 108 embedded therein. In FIG. 1, the wire is depicted as in the mid portion of the pane of glass 104.
One reason for the dangers posed by conventional wire glass is that conventional wire glass does not meet current minimum safety glazing standards, which require impact resistance to an impact of about 100 foot pounds as measured using methods described in CPSC standard 16 C.F.R. 1201. Greater stresses can cause substantial breakage of conventional wire glass, and can result in the production of dangerous shards.
Prior art solutions to the problem include the use of tempered glass in the transparent structure. Unfortunately, tempered glass is poorly suited because it generally does not withstand the “hose stream” portion of fire testing as required by building codes. Steel bars, gratings or external mesh have also be added to provide increased impact resistance. However, gratings and the like can significantly increase the cost of production, the bulk of the structure, and can decrease visibility through the glass.